Undesirable airborne compounds, including sulfur compounds, ammonia, formaldehyde, urea, carbon monoxide, oxides of nitrogen, mercaptans, amines, and ethylene, occur in a number of environments, where most are primarily responsible for the presence of disagreeable odors, or irritating or toxic gases. Such environments include petroleum treatment and storage areas, sewage treatment facilities, hospitals, morgues, anatomy laboratories, animal rooms, and pulp and paper production sites, among others. These undesirable compounds may be bacterial breakdown products of higher organic compounds, or by products of industrial processes.
Hydrogen sulfide ("H.sub.2 S"), a colorless, toxic gas with a characteristic odor of rotten eggs, is produced in coal pits, gas wells, sulfur springs, and from decaying organic matter containing sulfur. Controlling emissions of this gas, particularly from municipal sewage treatment plants, has long been considered desirable. More recently, protecting electronic apparatus from the corrosive fumes of these compounds has become increasingly important. Further, H.sub.2 S is flammable.
Ammonia ("NH.sub.3 "), also a colorless gas, possesses a distinctive, pungent odor and is a corrosive, alkaline gas. The gas is produced in animal rooms and nurseries and its control also has long been considered desirable.
Chlorine ("Cl.sub.2 ") is a greenish-yellow gas with a suffocating odor. The compound is used for bleaching fabrics, purifying water, treating iron, and other uses. Control of this powerful irritant is most desirable for the well-being, of those who work with it or are otherwise exposed to it. At lower levels, in combination with moisture, chlorine has a corrosive effect on electronic circuitry, stainless steel and the like.
Formaldehyde ("HCHO") is a colorless gas with a pungent suffocating odor. It is present in morgues and anatomy laboratories, and because it is intensely irritating to mucous membranes, its control is desirable.
Urea ("CH.sub.4 N.sub.2 O") is present in toilet exhaust and is used extensively in the paper industry to soften cellulose. Its odor makes control of this compound desirable.
Carbon monoxide ("CO"), an odorless, colorless, toxic gas, is present in compressed breathing air. Oxygenation requirements for certain atmospheres, including those inhabited by humans, mandate its control.
Oxides of nitrogen including nitrogen dioxide ("NO.sub.2 "), nitric oxide ("NO"), and nitrous oxide ("N.sub.2 O"), are compounds with differing characteristics and levels of danger to humans, with nitrous oxide being the least irritating oxide. Nitrogen dioxide, however, is a deadly poison. Control of pollution resulting from any of these oxides is desirable or necessary, depending on the oxide.
Mercaptans and amines, including methyl mercaptan ("CH.sub.3 SH"), butyl mercaptan ("C.sub.4 H.sub.9 SH") and methyl amine ("CH.sub.5 N"), are undesirable gases present in sewerage odor. The control of these gases is desired for odor control.
Ethylene ("C.sub.2 H.sub.4 ") is a colorless, flammable gas that is a simple asphyxiant which accelerates the maturation or decomposition of fruits, vegetables, and flowers. Control of this compound prolongs the marketable life of such items.
Attempts have been made to provide fiber filters for the removal of the undesirable compounds from fluid streams. Desired features of such fiber filters are a high efficiency in removing the compound from an air stream contacting the fiber filter, and a high ignition temperature (non-flammability).
One specific example of a fiber filter for the removal of undesirable compounds from gas streams is the Odor Kontroller.RTM. line of filters available from Air-Kontrol, of Batesville, Miss. The Odor Kontroller.RTM. filters are non-woven polyester coated with crushed, activated carbon, which can be impregnated for removing reactive gases.
Air-Kontrol also markets a fiber filter specific for the removal of ammonia and ammonium compounds. This fiber filter is Zeo-Sorb Odor Kontroller.RTM., which is non-woven polyester coated with crushed zeolite. The Air-Kontroller.RTM. filters are also available coated with an antimicrobial composition to remove organisms from an air stream.
Another example of a fiber filter is AAF-NWPE, available from LEWCOTT of Millbury, Mass. The AAF-NWPE fiber filter is non-woven polyester coated with activated alumina. Also available from LEAWCOTT is ZEF-NWPE, which is non-woven polyester coated with zeolite.
Although the above filters disclose non-woven polyester coated with activated carbon, zeolite, or activated alumina for the removal of undesirable compounds from fluid streams, this line of filters has a limited efficiency for the removal of undesired compounds.
Accordingly, although there are a few fiber filters known in the art for removing undesirable contaminants from fluid streams, as discussed above, these known fiber filters all have a limited efficiency for the removal of undesirable compounds from gas streams, and therefore have limitations and drawbacks in their use, and do not meet the needs of various industries.
Therefore, there remains a need in the art for a fiber filter that has a high efficiency for the removal of undesired compounds from a fluid stream. More particularly, there remains a need in the art for a fiber filter that has the capability of both absorbing or adsorbing an undesirable compound and neutralizing or oxidizing an undesirable compound. Further, this fiber filter needs to be of low flammability, long lasting, requiring fewer replacements, and thereby minimizing replacement and maintenance costs. Also needed is a high efficiency fiber filter which may be used in small filter beds, and therefore may allow the treatment of fluid streams where there are significant space limitations.